| O.J. 121 | 121 Spring St. | 212-343-2706 |
| O.J.S. Art Gallery | 883 First Ave. | 212-758-4206 |
| O.K. Harris Work of Art | 383 W Broadway | 212-431-3600 |
| O'Hara Gallery | 41 E 57th St. | 212-355-3330 |
| O'Sullivan Antiques | 51 E 10th St. | 212-260-8985 |
| Objets Plus | 315 E 62nd St. | 212-832-3386 |
| Objets Trouves Antiques | 217 E 60th St. | 212-753-0221 |
| Oblique Galleries, Inc. formerly Langham Leff Gallery | 210 E 60th St. | 212-421-8338 |
| Odile Gorse | 159 Madison Ave, Ste 8H | 212-683-0163 |
| Odyssia | 305 E 61st St. | 212-486-7338 |
| Oil & Steel Gallery | Long Island City. 30-40 Vernon Blvd. | 718-545-5707 |
| Oil Lamps | 110 W 25th St., #308 | 212-255-6584 |
| Old Print Shop, The | 150 Lexington Ave. | 212-683-3950 |
| Old Versailles | 315 E 62nd St. | 212-421-3663 |
| Olde Good Things | 124 W 24th St. | 212-989-8401 |
| Oliphant & Co. | 1120 Lexington Ave. | 212-439-0007 |
| One Great Jones | 1 Great Jones | 212-460-8456 |
| Onetwentyeight | 128 Rivington St. | 212-674-0244 |
| Open Interactive Media | 73 Franklin St. | 212-343-2510 |
| Opera Gallery | 115 Spring St. | 212-966-6675 |
| Oriental Art | 110 W 25th St., 2nd fl. | 212-924-8779 |
| Oriental Gallery | 13-17 Elizabeth St. | 212-226-8461 |
| Orientations Gallery | 802 Madison Ave. | 212-772-7705 |
| Osiris | 20 Greene St. | 212-925-8786 |
| Ostia Inc. | 1050 Second Ave., #15 | 212-371-2424 |
| Otto Naumann | 22 E 80th St. | 212-734-4443 |
| Ozone Art Gallery | 100 Kenmare St. | 212-965-1719 |
| Owen Gallery | 19 E 75th St. | 212-879-2415 |